How does vitrified polyolefin cable material achieve high-temperature ceramicization?
Release Time : 2025-08-28
In modern buildings and transportation infrastructure, the safe operation of power systems is directly related to the success of personnel evacuation, fire coordination, and emergency rescue. In the event of a fire, the insulation of ordinary cables often softens, melts, and drips rapidly at high temperatures, leading to short circuits, power outages, and even secondary disasters. To address this challenge, a new high-performance refractory material—vitrified polyolefin cable material—has emerged. It not only possesses the environmentally friendly, flame-retardant, and low-smoke properties of traditional low-smoke, halogen-free cable materials, but also "self-transforms" under flame conditions to form a hard, dense ceramic-like shell, achieving true "fire-resistant, uninterrupted power supply."
1. The Essence of Ceramics: Structural Reconstruction from Organic to Inorganic
"Ceramicization" is not a literal transformation into ceramic; rather, it involves a synergistic chemical and physical transformation process occurring at high temperatures. Vitrified polyolefin cable material uses a polyolefin (such as polyethylene and polypropylene) as a matrix. By adding ceramic fillers (such as mica, silicates, borates, and glass microspheres) and functional additives (such as ceramic-forming catalysts, flame retardants, and crosslinking agents) in specific proportions, the resulting composite system is a flexible polymer at room temperature that transforms into an inorganic hard shell at high temperatures. When the cable is exposed to fire and the temperature rises above 550°C, the polyolefin matrix begins to pyrolyze, releasing combustible gases and gradually carbonizing. Simultaneously, the ceramic filler undergoes a melting and sintering reaction under the influence of the high temperature and catalyst, bonding with the carbonized skeleton to form a continuous silicon-oxygen network. This process is similar to the firing of ceramics, ultimately forming a complete, dense, and hard inorganic glass-ceramic composite shell on the cable conductor surface. This shell is not only non-flammable but also has extremely low thermal conductivity, effectively isolating the heat from external flames and protecting the internal conductor from electrical damage, maintaining electrical function even after hours of high-temperature combustion.
2. Material Design: The Key to Achieving Stable Vitrification
The performance of vitrified polyolefin cable materials is highly dependent on their formulation and processing. First, the selection and proportion of ceramic fillers are crucial. Fillers must possess a high melting point, a low coefficient of thermal expansion, and good high-temperature chemical stability. For example, mica strengthens the shell's layered structure, while borates help lower the sintering temperature and promote densification. Second, ceramic-forming catalysts (such as metal oxides) accelerate the formation of the inorganic network, ensuring a rapid completion of the ceramic reaction. Furthermore, crosslinking techniques (such as peroxide or silane crosslinking) are often incorporated into the material to enhance the cable material's mechanical strength and thermal stability at room temperature, preventing deformation due to overheating before ignition. At high temperatures, the crosslinked structure also provides support for the carbon skeleton, facilitating the uniform formation of the ceramic layer.
3. Processing Advantages: Ensuring Uniform and Stable Performance
vitrified polyolefin cable materials utilize an advanced process combining pre-mixing in an internal mixer and plasticizing and extruding in a twin-screw extruder. The internal mixer vigorously shears and mixes the raw materials under high temperature and pressure, ensuring thorough dispersion of the ceramic fillers, additives, and polyolefin matrix, preventing agglomeration or uneven distribution. Subsequently, the twin-screw extruder further homogenizes the materials, achieving highly uniform composition. This processing method not only improves batch stability but also ensures uniform thickness and smooth surface finish of the extruded cable insulation and jacket, laying a solid foundation for subsequent high-temperature vitrification.
4. Performance: Dense Shell, Strong and Fireproof
Flame combustion tests have shown that the ceramic shell formed from vitrified polyolefin cable material exhibits high hardness, low porosity, and strong thermal shock resistance. Its dense structure effectively blocks the penetration of flames, heat, and oxygen, while also preventing molten droplets from spreading fire. In tests based on standards such as IEC60331, fire-resistant cables made from this material can withstand flames at 950°C for over 90 minutes, meeting fire protection requirements for critical locations such as high-rise buildings, subways, and tunnels.
Vitrified polyolefin cable material, through an organic-inorganic synergistic transformation mechanism, achieves intelligent transformation from a flexible insulation material to a rigid fire barrier. It is not only an innovative achievement in materials science but also a crucial safeguard for building electrical safety. With the acceleration of urbanization and rising fire safety standards, this new cable material, capable of high-temperature ceramicization, is becoming an indispensable "fireproof core" for fire-resistant building pipelines and emergency power supply systems, providing an invisible yet robust defense against the dangers of life and property.
1. The Essence of Ceramics: Structural Reconstruction from Organic to Inorganic
"Ceramicization" is not a literal transformation into ceramic; rather, it involves a synergistic chemical and physical transformation process occurring at high temperatures. Vitrified polyolefin cable material uses a polyolefin (such as polyethylene and polypropylene) as a matrix. By adding ceramic fillers (such as mica, silicates, borates, and glass microspheres) and functional additives (such as ceramic-forming catalysts, flame retardants, and crosslinking agents) in specific proportions, the resulting composite system is a flexible polymer at room temperature that transforms into an inorganic hard shell at high temperatures. When the cable is exposed to fire and the temperature rises above 550°C, the polyolefin matrix begins to pyrolyze, releasing combustible gases and gradually carbonizing. Simultaneously, the ceramic filler undergoes a melting and sintering reaction under the influence of the high temperature and catalyst, bonding with the carbonized skeleton to form a continuous silicon-oxygen network. This process is similar to the firing of ceramics, ultimately forming a complete, dense, and hard inorganic glass-ceramic composite shell on the cable conductor surface. This shell is not only non-flammable but also has extremely low thermal conductivity, effectively isolating the heat from external flames and protecting the internal conductor from electrical damage, maintaining electrical function even after hours of high-temperature combustion.
2. Material Design: The Key to Achieving Stable Vitrification
The performance of vitrified polyolefin cable materials is highly dependent on their formulation and processing. First, the selection and proportion of ceramic fillers are crucial. Fillers must possess a high melting point, a low coefficient of thermal expansion, and good high-temperature chemical stability. For example, mica strengthens the shell's layered structure, while borates help lower the sintering temperature and promote densification. Second, ceramic-forming catalysts (such as metal oxides) accelerate the formation of the inorganic network, ensuring a rapid completion of the ceramic reaction. Furthermore, crosslinking techniques (such as peroxide or silane crosslinking) are often incorporated into the material to enhance the cable material's mechanical strength and thermal stability at room temperature, preventing deformation due to overheating before ignition. At high temperatures, the crosslinked structure also provides support for the carbon skeleton, facilitating the uniform formation of the ceramic layer.
3. Processing Advantages: Ensuring Uniform and Stable Performance
vitrified polyolefin cable materials utilize an advanced process combining pre-mixing in an internal mixer and plasticizing and extruding in a twin-screw extruder. The internal mixer vigorously shears and mixes the raw materials under high temperature and pressure, ensuring thorough dispersion of the ceramic fillers, additives, and polyolefin matrix, preventing agglomeration or uneven distribution. Subsequently, the twin-screw extruder further homogenizes the materials, achieving highly uniform composition. This processing method not only improves batch stability but also ensures uniform thickness and smooth surface finish of the extruded cable insulation and jacket, laying a solid foundation for subsequent high-temperature vitrification.
4. Performance: Dense Shell, Strong and Fireproof
Flame combustion tests have shown that the ceramic shell formed from vitrified polyolefin cable material exhibits high hardness, low porosity, and strong thermal shock resistance. Its dense structure effectively blocks the penetration of flames, heat, and oxygen, while also preventing molten droplets from spreading fire. In tests based on standards such as IEC60331, fire-resistant cables made from this material can withstand flames at 950°C for over 90 minutes, meeting fire protection requirements for critical locations such as high-rise buildings, subways, and tunnels.
Vitrified polyolefin cable material, through an organic-inorganic synergistic transformation mechanism, achieves intelligent transformation from a flexible insulation material to a rigid fire barrier. It is not only an innovative achievement in materials science but also a crucial safeguard for building electrical safety. With the acceleration of urbanization and rising fire safety standards, this new cable material, capable of high-temperature ceramicization, is becoming an indispensable "fireproof core" for fire-resistant building pipelines and emergency power supply systems, providing an invisible yet robust defense against the dangers of life and property.